2. Develop ultrafast OCT systems for imaging of the macula and optic nerve head. Although current FD-OCT technology at 26 kHz represents a tremendous advance over standard 400 Hz TD-OCT (Zeiss Stratus), it still takes ~4 seconds for a full 3-dimensional (3D) raster scan of the macula. Our goal is to reduce this time to 0.1-0.2 second so 3D scans will be minimally affected by eye movement. This requires an ultrafast speed of 500-1000 kHz. We plan to adapt the Fourier-domain modelocked-laser (FDML) swept-source OCT, which has already been demonstrated at 249 kHz at MIT. We will further improve its speed to 500 kHz. The short integration time and phase stability of FDML-OCT is ideal for Doppler perfusion measurement (see next aim). For an even faster speed, parallel line-scan FD-OCT at 1 MHz will be developed. Line-scan OCT is not suitable for Doppler flow measurement due to the relatively long integration time, but is more efficient for ultrafast anatomic imaging. It will allow full 8x8 mm macular 3D imaging in 0.2 second. We will also continue to develop polarization-sensitive (PS) OCT for NFL birefringence measurement, which will also be greatly enhanced by higher speed and greater averaging to suppress noise.